Epithelial Changes in the Testosterone-Dominant Vagina: Implications for Menopause, Transgender Care, and Beyond

Hormonal fluctuations across female life stages drive numerous transcriptomic and epigenetic changes, yet the effects of sex hormones on mucosal immunity, particularly in the vaginal epithelium, remain poorly understood. The vaginal mucosa undergoes cyclical remodeling during the ovulatory cycle under the influence of estrogens and progesterone produced mainly in the ovary. The ovary can also be a source of testosterone, and in postmenopausal women, as well as transgender men receiving hormone therapy, phenotypic changes in the vagina due to increased testosterone have been observed. However, the consequences of testosterone dominance in this tissue in terms of resilience and inflammation have not been well characterized. The goal of this study was to identify the histological and immunological changes within the vaginal epithelial cell barrier in an estrogen- vs. testosterone-dominant environment using an established in vitro reconstructed vaginal epithelial tissue model. Compared to estradiol, exposure to testosterone resulted in a thinner tissue with alterations in the cornification, although no impairment in the epithelial barrier was detected. Each hormone also resulted in a unique RNA expression profile, including increased expression of tight junction genes and decreased expression of chemokines and their receptors in testosterone compared to estradiol exposure. These data have implications for women's health, including menopause, transgender men using gender-affirming hormone therapy, and other conditions associated with high testosterone in the vaginal compartment.